Emma Stone says she has only ever received the same pay as her male co-stars when they have taken a voluntary cut out of a sense of fairness.

The award-winning actress said women in Hollywood are paid 20% less than their male counterparts "at best".

"In my career so far, I've needed my male co-stars to take a pay cut so that I may have parity with them," said the 28-year-old. "That's something they do for me because they feel it's what's right and fair."

Image:Stone won a BAFTA, Oscar and Golden Globe for her role in La La Land

Stone made the comments in an interview with tennis champion Billie Jean King, who she is playing in new film Battle of the Sexes.

The film dramatises the 1973 tennis match between King and Bobby Riggs, a male tennis player who claimed he would be able to beat her in a direct competition.

King won the match in straight sets in a turning point for women's tennis.

Now 73, she said she thought Stone's experiences suggested men were "vital" to progress in equal pay.

"They're usually in the power position, and if they start to change the paradigms, things start to shift," she said.

1:22

Video:Emma Stone: 'La La Land was a deep dive of an experience'

Stone's Battle of the Sexes co-star Andrea Riseborough also said she had been paid less than men even when playing a leading role, despite having asked for a rise.

"There's this underlying feeling that you should be grateful," she said.

More from Emma Stone

They showed Jennifer Lawrence, the highest-paid actress in Hollywood, had been paid less than her male co-stars in American Hustle, earning 7% of the movie's profits compared to Christian Bale and Bradley Cooper's 9%.

A list compiled by Forbes in 2016 showed the 10 highest paid actresses in Hollywood earned $205m (£159m) between them - less than half the sum earned by male stars.